Crevice scaling laws to investigate local hydrogen uptake in rescaled model occluded sites
Autor: | John R. Scully, Jason S. Lee, Michael A. Switzer |
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Rok vydání: | 2008 |
Předmět: | |
DOI: | 10.1016/b978-008044635-6.50010-8 |
Popis: | Publisher Summary This chapter presents the effects of occluded site geometry and electrochemical conditions on local hydrogen production and uptake in a precipitation age-hardened Fe-13Cr-8Ni-2Mo-1Al stainless steel. The x2/gap scaling law, where x is the pit/crevice depth and “gap” is the pit/crevice width, was utilized to rescale the sizes of model pits from micrometer to millimeter-scale dimensions. Such rescaling enabled local hydrogen measurements as a function of rescaled pit depth. The rescaled pit specimens were potentiostatically charged under conditions where the pit mouth resided in the passive region and H uptake was possible given sufficient IR drop at a certain pit depth. Specimens were held under these conditions until uniformly charged from interior surfaces according to the H diffusivity in PH 13-8 Mo. Microreference electrode measurements recorded local pit potential as a function of pit depth, x, using a micrometer resolution positioning system. Rescaled pit specimens were exposed, removed, rinsed, stored in LN2, and sectioned radially for H analysis versus depth x. The pit exhibits a 150 mV potential drop from its mouth to its bottom. Most of the potential drop occurs in the first 10 mm of depth, consistent with the modeling results. |
Databáze: | OpenAIRE |
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